CN112019254A - Active low-delay routing method for low-earth-orbit satellite network - Google Patents

Active low-delay routing method for low-earth-orbit satellite network Download PDF

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CN112019254A
CN112019254A CN202010793790.9A CN202010793790A CN112019254A CN 112019254 A CN112019254 A CN 112019254A CN 202010793790 A CN202010793790 A CN 202010793790A CN 112019254 A CN112019254 A CN 112019254A
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satellite
hop
neighbor
hop neighbor
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CN112019254B (en
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窦宏浩
李常亮
杨彪
章雷
刘丽
张世杰
何文婷
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CASIC Space Engineering Development Co Ltd
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Abstract

One embodiment of the invention discloses a low earth orbit satellite network active low time delay routing method, which comprises the following steps: s100, calibrating routing processing transmission time delay D of each satellite nodeHS(ii) a S102, counting queue forwarding waiting time delay D of each satellite node in real timeQW(ii) a S104, calculating the inter-satellite transmission time delay D of two adjacent satellite nodesij(ii) a S106, each satellite node is in a statistical time window TsaInternally counting the forwarding waiting time delay D of all queues of the satellite on each portQWAnd routing processing transmission delay DHSAnd forming neighbor probing message NeighborMsg, NeighborMsg message to count the time window TsaTransmitting at each port of an inter-satellite link for a transmission period; s108, after receiving the NeighborMsg message, other satellite nodes except the satellite generate a one-hop neighbor table, a two-hop neighbor table and a network topology table according to the NeighborMsg message; and S110, calculating the routing table of the local satellite through the generated one-hop neighbor table, two-hop neighbor table and network topology table.

Description

Active low-delay routing method for low-earth-orbit satellite network
Technical Field
The invention relates to the technical field of satellite communication. And more particularly, to an active low-delay routing algorithm for a low-earth orbit satellite network.
Background
In a low-orbit satellite constellation communication network system, each satellite node in the network can perform data communication and information interaction between satellites through an inter-satellite communication link (an inter-satellite link for short), so that full constellation network data transmission is realized, and global blind-spot-free coverage is achieved. At present, low-orbit broadband satellite communication systems based on inter-satellite link networking have been proposed or are being built by multiple companies such as SpaceX and the like, and the realization of large-scale low-orbit satellite networking by using inter-satellite links becomes one of the main development trends of communication satellite systems.
The low earth orbit satellite constellation system realizes the transmission of various load data between satellites through a network formed by inter-satellite links, and on-satellite routes play an important role in route switching and forwarding. How to find an optimal transmission path from a service source satellite to a service destination satellite is the core function of an on-satellite routing algorithm. The shortest hop count (the number of relay forwarding times from a service source satellite to a service destination satellite is the minimum) is usually adopted as a basis for selecting an inter-satellite forwarding path, but the path selected based on the shortest hop count is often not an optimal path, and particularly for delay sensitive services, the requirement on transmission delay of a data packet is high, and the shortest hop count routing transmission path is not necessarily the minimum delay routing transmission path.
Disclosure of Invention
To solve at least one of the above problems, it is an object of the present invention to provide a proactive low-delay routing method for a low-earth orbit satellite network.
In order to achieve the purpose, the invention adopts the following technical scheme:
an active low-delay routing method for a low-earth orbit satellite network, the method comprising:
s100, calibrating routing processing transmission time delay D of each satellite nodeHS；
S102, counting queue forwarding waiting time delay D of each satellite node in real timeQW；
S104, calculating the inter-satellite transmission time delay D of two adjacent satellite nodesij；
S106, each satellite node is in a statistical time window TsaInternally counting the forwarding waiting time delay D of all queues of the satellite on each portQWAnd routing processing transmission delay DHSAnd forming neighbor probing message NeighborMsg, NeighborMsg message to count the time window TsaTransmitting at each port of an inter-satellite link for a transmission period;
s108, after other satellite nodes except the satellite receive the NeighborMsg message, generating a one-hop neighbor table, a two-hop neighbor table and a network topology table according to the NeighborMsg message;
s110, calculating the routing table of the local satellite through the generated one-hop neighbor table, two-hop neighbor table and network topology table.
In a specific embodiment, the S100 further includes:
s1000, processing and sending time delay D in calibration routingHSThe forward waiting queue is emptied;
s1002, clearing the forwarding waiting queue, and receiving a data packet from a port of the router at a time TRRStarting at the moment T when the data packet completes the code modulation at the baseband of the inter-satellite linkBTAnd (4) ending, namely:
DHS＝TBT-TRR。
in a specific embodiment, the S102 further includes:
the on-board switching forwarding router distributes a forwarding waiting queue for different QoS priority services, data packets in the same queue are sent according to a first-in first-out principle, different queues are scheduled according to a priority scheduling strategy, and the waiting time of each data packet in the queues is dequeuing time ToutAnd the enqueue time TinThe difference of (a) is:
DQW＝Tout-Tin。
in a specific embodiment, the S104 further includes:
each satellite stores full-network ephemeris information, and the position coordinates of i star and j star of two adjacent satellites are PiAnd PjThe relative distance between the i star and the j star can be obtained according to the position coordinates, and further the transmission time delay D between the i star and the j star can be obtainedijNamely:
Figure BDA0002624732620000021
wherein C is the speed of light.
In a specific embodiment, the neighbor detection message NeighborMsg content includes: local satellite ID, route processing and sending time delay DHSForwarding wait delay DQWMessage sequence number SnNumber of message transfers HnOne-hop neighbor satellite ID, one-hop neighbor satellite communication state and inter-satellite transmission time delay Dij。
In a specific embodiment, the S108 further includes:
s1080, after other satellite nodes except the local satellite receive the NeighborMsg message, the ' local satellite ID ' and the ' message serial number S in the NeighborMsg message are utilizedn"make duplicate checking judgment, if received, discard the NeighborMsg message, otherwise, go to S1082;
s1082, judging message forwarding times HnIf yes, the message sending star is the one-hop neighbor node of the local star, a corresponding entry of the local star ID in the one-hop neighbor table is newly established or updated, and the local star ID and the message serial number S in the NeighborMsg message are recorded in the entryn"," routing process transmission delay DHS"," queue forwarding waiting delay DQW"," one-hop neighbor satellite ID "," one-hop neighbor satellite connection state ", and" inter-satellite transmission delay Dij”；
S1084, if the 'one-hop neighbor satellite connection state' corresponding to a certain 'one-hop neighbor satellite ID' in the NeighborMsg message is bidirectional, the 'one-hop neighbor satellite ID'The node is a two-hop neighbor node of the satellite, an entry corresponding to the one-hop neighbor satellite ID is newly built or updated in a two-hop neighbor table, and the newly built or updated content comprises routing processing transmission delay DHS"," queue forwarding waiting delay DQW"," forward hop satellite ID ", and" inter-satellite transmission delay Dij”；
S1086, judging message forwarding times HnIf the neighbor satellite ID exists in the neighbor list of one hop or the neighbor list of two hops, skipping and not processing; otherwise, judging whether the connection state of the one-hop neighbor satellite ID is bidirectional, and if not, skipping and not processing; if the connection is bidirectional, an entry corresponding to the local star ID in the NeighborMsg message is newly built or updated in the network topology table, and the local star ID and the message sequence number S in the NeighborMsg message are recorded in the entryn"," routing process transmission delay DHS"," queue forwarding waiting delay DQW", one-hop neighbor satellite ID and inter-satellite transmission delay D of the bidirectional connection stateij”。
In a specific embodiment, the S110 further includes:
s1100, when calculating each hop route, calculating the total time delay D of the hophThe formula is as follows:
Dh＝DHS+DQW+Dij；
when calculating H-hop route, according to D of each hophAnd calculating the total time delay D according to the following formula:
Figure BDA0002624732620000031
s1102, clearing all table entries in the existing routing table;
s1104, calculating a 1-hop route through the one-hop neighbor table, specifically comprising the following steps:
acquiring the nth neighbor satellite ID of the satellite according to the one-hop neighbor table;
computing stationThe time delay from the local satellite to the nth 1-hop neighbor satellite is as follows: dh_1＝DHS_1+DQW_1+Dij_1；
Traversing N from 1 to N, wherein N one-hop neighbor nodes of the local satellite are provided, and the time delay of the N one-hop neighbor nodes corresponding to the local satellite is recorded in a one-hop neighbor table;
s1106, 2-hop routing is calculated through the two-hop neighbor table, for any two-hop neighbor, a table entry exists in the two-hop neighbor table, and the ID of the previous-hop satellite is equal to one-hop neighbor of the current satellite, so the specific steps of calculating the 2-hop routing table entry of each two-hop neighbor are as follows:
acquiring the Mth 2-hop neighbor satellite ID of the satellite according to the two-hop neighbor table;
calculating the time delay from the local satellite to the m 2-hop neighbor satellite as follows: dh_2＝Dh_1+DHS_2+DQW_2+Dij_2；
Traversing M from 1 to M, wherein M neighbor nodes of the satellite have M, and the two-hop neighbor table records the time delay of the M neighbor nodes of the satellite corresponding to the M neighbor nodes, wherein Dh_1Representing the time delay from the satellite to the one-hop neighbor node corresponding to the satellite;
s1108, calculating h +1 hop routing through a network topology table, wherein h is a natural number greater than or equal to 2, and the specific steps are as follows:
if the satellite ID of an entry in the network topology table exists in the routing table and the routing hop number is equal to h, judging the 'one-hop neighbor satellite node' of the entry as follows;
if the 'one-hop neighbor satellite node' has a corresponding entry in the routing table, performing time delay comparison; otherwise, the one-hop neighbor satellite node is a new h + 1-hop node, and the routing entry of the h + 1-hop node is calculated;
acquiring the ID of the kth + 1-hop neighbor satellite of the satellite according to the h + 1-hop neighbor table;
calculating the time delay from the satellite to the k h + 1-hop neighbor satellite as follows: dh_h+1＝Dh_h+DHS_h+1DQW_h+1+Dij_h+1；
Traversing K from 1 to K, wherein K neighbor nodes of all h +1 hops of the satellite are provided, and the h +1 hop neighbor table records the time delay of the K neighbor nodes of the satellite corresponding to the K neighbor nodes of the satellite, wherein if 1 or more paths exist from the satellite to the h +1 hop neighbor nodes, the path with shorter time delay is reserved, and Dh_hAnd representing the time delay from the satellite to the h-hop neighbor node corresponding to the satellite.
In one embodiment, the H of NeighborMsgn+1, when the number of times of forwarding Hn+1≤HmaxWhen, the NeighborMsg message is forwarded, otherwise it is not forwarded, where HmaxThe maximum forwarding times of the whole network.
The invention has the following beneficial effects:
the active low-delay routing algorithm for the low-orbit satellite network can realize real-time statistics of end-to-end delay of service satellites with different priorities through whole network period updating calculation according to routing processing delay, queue waiting delay and inter-satellite transmission delay, obtains a minimum delay path through calculation, provides a low-delay routing algorithm for delay sensitive services in the low-orbit satellite network, and effectively reduces inter-satellite transmission delay.
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The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
Fig. 1 shows a flowchart of an embodiment of a proactive low-delay routing method for a low-earth orbit satellite network according to the present application.
Fig. 2 shows a schematic diagram of a neighbor node connected state detection process.
Fig. 3 shows a schematic diagram of a local NeighborMsg message cycle sending process.
Fig. 4 shows a schematic diagram of the route calculation and NeighborMsg message processing procedure.
Detailed Description
In order to more clearly illustrate the invention, the invention is further described below with reference to preferred embodiments and the accompanying drawings. Similar parts in the figures are denoted by the same reference numerals. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.
Fig. 1 shows a flow chart of an embodiment of a low earth orbit satellite network proactive low delay routing method according to the present application. A low earth orbit satellite network active low time delay routing method includes the following steps:
s100, calibrating routing processing transmission time delay D of each satellite nodeHS。
In a specific embodiment, the S100 further includes:
s1000, processing and sending time delay D in calibration routingHSThe forward waiting queue is emptied;
s1002, clearing the forwarding waiting queue, and receiving a data packet from a port of the router at a time TRRAt the beginning, the data packet completes the code modulation at the baseband of the intersatellite linkBTAnd (4) ending, namely:
DHS＝TBT-TRR。
in one specific example, the routing process transmission delay D is calibratedHSTime, queue forwarding waiting time delay D cannot be introducedQWTherefore, the forwarding waiting queue needs to be cleared before the routing processing transmission delay is calibrated. After the forwarding waiting queue is emptied, the control routing port generates a data packet DB _1 and records the time as TRR-1Recording the time T when the inter-satellite baseband processing unit completes the coding modulation on the data packet DB _1BT-1If the routing processing transmission delay of the data packet DB _1 is DHS-1＝TBT-1-TRR-1. Total statistic N1Routing processing and transmitting time delay of the packet data, wherein the average value of the routing processing and transmitting time delay is calibrated routing processing and transmitting time delay D such as the current calibrationHSNamely:
Figure BDA0002624732620000051
wherein N is1Is a natural number, i is more than or equal to 1 and less than or equal to N1。
S102, counting queue forwarding waiting of each satellite node in real timeTime delay DQW。
In a specific embodiment, the S102 further includes:
the on-board switching forwarding router distributes a forwarding waiting queue for different QoS priority services, data packets in the same queue are sent according to a first-in first-out principle, different queues are scheduled according to a priority scheduling strategy, and the waiting time of each data packet in the queues is dequeuing time ToutAnd the enqueue time TinThe difference of (a) is:
DQW＝Tout-Tin
the QoS is called "quality of service" in chinese, and is a security mechanism of a network, and is a technology for solving problems such as network delay and congestion.
In a specific example, the waiting time of different priority level data packets in different queues is different, and the routing method counts Q queue forwarding waiting time delays DQWIn the statistic queue q, total statistic N2The average value of each data packet is queue q, and the forwarding waiting time delay is DQW_qNamely:
Figure BDA0002624732620000061
in the formula, N2Is a natural number, i is more than or equal to 1 and less than or equal to N2，Tin_iIs the enqueue time of the ith packet data, Tout_iIs the dequeue time of the ith packet data.
S104, calculating the inter-satellite transmission time delay D of two adjacent satellite nodesij。
In a specific embodiment, the S104 further includes:
each satellite stores full-network ephemeris information, and the position coordinates of i star and j star of two adjacent satellites are PiAnd PjThe relative distance between the i star and the j star can be obtained according to the position coordinates, and further the transmission time delay D between the i star and the j star can be obtainedijNamely:
Figure BDA0002624732620000062
wherein C is the speed of light.
S106, each satellite node is in a statistical time window TsaInternally counting the forwarding waiting time delay D of all queues of the satellite on each portQWAnd routing processing transmission delay DHSAnd forming neighbor probing message NeighborMsg, NeighborMsg message to count the time window TsaAnd transmitting at each port of the inter-satellite link for a transmission period.
In a specific embodiment, the neighbor detection message NeighborMsg content includes: local satellite ID, route processing and sending time delay DHSForwarding wait delay DQWMessage sequence number SnNumber of message transfers HnOne-hop neighbor satellite ID, one-hop neighbor satellite communication state and inter-satellite transmission time delay Dij。
In a specific example, fig. 2 is a schematic diagram illustrating a neighbor node connected state detection process. When A starts to send a NeighborMsg message to B, the neighbor node is empty, the node A is added as a one-way neighbor node after the B receives the NeighborMsg message sent by A, the B sends the message again, the node B is added as a two-way neighbor node after the A receives the message sent by the B, the A sends the NeighborMsg message to the B, and the B updates the node A to be a two-way neighbor node and sends the message in a circulating mode.
In a specific example, a schematic diagram of a local NeighborMsg message periodic sending process is shown in fig. 3. Firstly, carrying out routing processing and sending time delay calibration on the satellite, then judging whether a NeighborMsg message sending period arrives, if so, carrying out transmission time delay calculation among the satellites, and then creating and sending the NeighborMsg message; if not, counting the queue forwarding time delay, judging whether the NeighborMsg message sending period arrives, and circularly performing the following steps.
And S108, after receiving the NeighborMsg message, other satellite nodes except the satellite generate a one-hop neighbor table, a two-hop neighbor table and a network topology table according to the NeighborMsg message.
In a specific embodiment, the S108 further includes:
s1080, after other satellite nodes except the local satellite receive the NeighborMsg message, the ' local satellite ID ' and the ' message serial number S in the NeighborMsg message are utilizednAnd performing duplicate checking judgment, if the message is received, discarding the NeighborMsg message, and otherwise, performing S1082.
S1082, judging message forwarding times HnIf yes, the message sending star is the one-hop neighbor node of the local star, a corresponding entry of the local star ID in the one-hop neighbor table is newly established or updated, and the local star ID and the message serial number S in the NeighborMsg message are recorded in the entryn"," routing process transmission delay DHS"," queue forwarding waiting delay DQW"," one-hop neighbor satellite ID "," one-hop neighbor satellite connection state ", and" inter-satellite transmission delay Dij”。
In a specific example, if the ID of the message sending star is not in the "one-hop neighbor satellite ID", it indicates that the message sending star has not received the NeighborMsg message of the message sending star, and sets the "one-hop neighbor satellite connection state" in the entry to be one-way, otherwise, it is two-way.
In one specific example, the "one-hop neighbor satellite ID" in the NeighborMsg message includes a plurality of satellite IDs, and the "other satellite IDs" other than the own satellite ID are two-hop neighbors of the own satellite.
S1084, if the one-hop neighbor satellite communication state corresponding to a certain one-hop neighbor satellite ID in the NeighborMsg message is bidirectional, the one-hop neighbor satellite ID node is a two-hop neighbor node of the same satellite, an item corresponding to the one-hop neighbor satellite ID is newly built or updated in a two-hop neighbor table, and the newly built or updated content comprises routing processing sending time delay DHS"," queue forwarding waiting delay DQW"," forward hop satellite ID ", and" inter-satellite transmission delay Dij”；
S1086, judging message forwarding times HnIf the neighbor satellite ID exists in the neighbor list of one hop or the neighbor list of two hops, skipping and not processing; otherwise, judging theWhether the connection state of the one-hop neighbor satellite ID is bidirectional or not is judged, and if not, the connection state is skipped and not processed; if the connection is bidirectional, an entry corresponding to the local star ID in the NeighborMsg message is newly built or updated in the network topology table, and the local star ID and the message sequence number S in the NeighborMsg message are recorded in the entryn"," routing process transmission delay DHS"," queue forwarding waiting delay DQW", one-hop neighbor satellite ID and inter-satellite transmission delay D of the bidirectional connection stateij”。
S110, calculating the routing table of the local satellite through the generated one-hop neighbor table, two-hop neighbor table and network topology table.
In one embodiment, each satellite node maintains a routing table that is stored to its satellite node in the network, and the routing table is computed based on a one-hop neighbor table, a two-hop neighbor table, and a network topology table that are locally stored by the node. To find a path from the source node to the farther node R, the connection pair (X, R) must be found, then the connection pair (Y, X) is found, and so on, until the Y node is found to be the source node itself. In order to make the path delay shortest, when calculating the route of each hop, the total delay D of the hop needs to be calculatedh。
S1100, when calculating each hop route, calculating the total time delay D of the hophThe formula is as follows:
Dh＝DHS+DQW+Dij；
when calculating H-hop routing, D of each hop is neededhAnd calculating the total time delay D according to the following formula:
Figure BDA0002624732620000081
in the formula, H is a natural number, i is more than or equal to 1 and less than or equal to H.
In one embodiment, FIG. 4 is a diagram illustrating a process for route calculation and NeighborMsg message processing. And establishing a routing table of each node according to the time delay D. The adding process of any node routing table can be divided into three parts: firstly, adding a one-hop neighbor node of the routing table, namely the hop count h is 1; secondly, adding two-hop neighbor nodes of the routing table, namely h is 2; finally, circularly adding nodes with hop number equal to h +1 (starting with h ═ 2) into the routing table, and describing the specific process as follows:
s1102, clearing all the entries in the existing routing table.
S1104, calculating a 1-hop route through the one-hop neighbor table, specifically comprising the following steps:
acquiring the nth neighbor satellite ID of the satellite according to the one-hop neighbor table;
calculating the time delay from the local satellite to the nth 1-hop neighbor satellite as follows: dh_1＝DHS_1+DQW_1+Dij_1；
And traversing N from 1 to N, wherein N one-hop neighbor nodes of the satellite are provided, and the time delay of the N one-hop neighbor nodes corresponding to the N one-hop neighbor nodes of the satellite is recorded in the one-hop neighbor table.
In one particular example of the use of the invention,
dest _ Sat _ ID is a neighbor satellite ID;
next _ Sat _ ID is the neighbor satellite ID;
the IFace is an intersatellite link port connected with a neighbor satellite;
Hop＝1；
time delay D with priority Qqh_1＝DqHS_1+DqQW_1+Dqij_1(ii) a In the formula DqQW_1Queue wait delay for Q priority, Dqij_1Is the inter-satellite transmission time delay from the node i to the adjacent satellite j (Dest _ Sat _ ID);
and circularly calculating the routing entry of each neighbor node in the one-hop neighbor table.
S1106, 2-hop routing is calculated through the two-hop neighbor table, for any two-hop neighbor, the two-hop neighbor table inevitably has such an entry, and if the previous-hop satellite ID is equal to one-hop neighbor of the current satellite, the specific steps of calculating the 2-hop routing entry of each two-hop neighbor are as follows:
acquiring the Mth 2-hop neighbor satellite ID of the satellite according to the two-hop neighbor table;
calculating the time delay from the local satellite to the m 2-hop neighbor satellite as follows: dh_2＝Dh_1+DHS_2+DQW_2+Dij_2；
Traversing M from 1 to M, wherein M neighbor nodes of the satellite have M, and the two-hop neighbor table records the time delay of the M neighbor nodes of the satellite corresponding to the M neighbor nodes, wherein Dh_1And the time delay from the local satellite to the one-hop neighbor node corresponding to the local satellite is represented.
In one specific example, Dest _ Sat _ ID is a two-hop neighbor satellite ID;
the Next _ Sat _ ID is the Next _ Sat _ ID of a certain routing table entry, and the Dest _ Sat _ ID of the routing table entry is equal to the ID of the previous hop satellite of the two-hop neighbor;
the IFace is the IFace of a certain routing table entry, and the Dest _ Sat _ ID of the routing table entry is equal to the ID of the previous hop satellite of the two-hop neighbor;
Hop＝2；
time delay D with priority Qq＝Dp_q+Dp_HS+Dp_qw+Dp_ij(ii) a In the formula Dp_qFor time delay to priority of forward-hopping satellite Q, Dp_HSRouting processing delay for forward-hop satellites, Dp_qwWaiting for a time delay for a queue of a forward-hop satellite Q priority service; dp_ijThe inter-satellite transmission time delay from a previous hop satellite i to a two-hop neighbor satellite j;
and circularly calculating the routing entry of each two-hop neighbor node in the two-hop neighbor table.
S1108, calculating h +1 hop routing through a network topology table, wherein h is a natural number greater than or equal to 2, and the specific steps are as follows:
if the satellite ID of an entry in the network topology table exists in the routing table and the routing hop number is equal to h, judging the 'one-hop neighbor satellite node' of the entry as follows;
if the 'one-hop neighbor satellite node' has a corresponding entry in the routing table, performing time delay comparison; otherwise, the one-hop neighbor satellite node is a new h + 1-hop node, and the routing entry of the h + 1-hop node is calculated;
acquiring the ID of the kth + 1-hop neighbor satellite of the satellite according to the h + 1-hop neighbor table;
calculating the time delay from the satellite to the k h + 1-hop neighbor satellite as follows: dh_h+1＝Dh_h+DHS_h+1DQW_h+1+Dij_h+1；
Traversing K from 1 to K, wherein K neighbor nodes of all h +1 hops of the satellite are provided, and the h +1 hop neighbor table records the time delay of the K neighbor nodes of the satellite corresponding to the K neighbor nodes of the satellite, wherein if 1 or more paths exist from the satellite to the h +1 hop neighbor nodes, the path with shorter time delay is reserved, and Dh_hAnd representing the time delay from the satellite to the h-hop neighbor node corresponding to the satellite.
In a specific example, if the satellite ID of an entry in the network topology table already exists in the routing table, and the number of routing hops is equal to h, the "one-hop neighbor satellite node" of the entry is determined as follows;
if the 'one-hop neighbor satellite node' has a corresponding entry in the routing table, performing time delay comparison; otherwise, the one-hop neighbor satellite node is a new h + 1-hop node. Calculating the h +1 hop node routing entry;
dest _ Sat _ ID is the satellite ID of the one-hop neighbor satellite node;
the Next _ Sat _ ID is the Next _ Sat _ ID of a certain routing table entry, and the Dest _ Sat _ ID of the routing table entry is equal to the satellite ID of an entry in the currently processed network topology table;
the IFace is the IFace of a certain routing table entry, and the Dest _ Sat _ ID of the routing table entry is equal to the satellite ID of the entry in the currently processed network topology table;
Hop＝h+1；
time delay D with priority Qq＝Dh_q+Dh_HS+Dh_qw+Dh_h+1(ii) a In the formula Dh_qFor time delay to the priority of h-hop satellites Q, Dh_HSRouting processing delay for h-hop satellite, Dh_qwWaiting for time delay for a queue of the h-hop satellite Q priority service; dh_h+1Is the inter-satellite transmission time delay from the h-hop satellite to the h + 1-hop satellite;
if the node is a new h +1 hop node, adding the content into a new entry of the routing table;
otherwise, comparing with the existing items, and updating or reserving the items with shorter time delay;
after the network topology table is traversed once, h is increased by 1, and the network topology table is traversed according to the steps;
the route calculation process ends with the satellite ID for which no entry exists in the network topology table already existing in the routing table and the number of route hops equals h.
In one embodiment, the H of NeighborMsgn+1, when the number of times of forwarding Hn+1≤HmaxWhen, the NeighborMsg message is forwarded, otherwise it is not forwarded, where HmaxThe maximum forwarding times of the whole network.
It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications may be included within the scope of the present invention.

Claims (8)

1. An active low-latency routing method for a low-earth orbit satellite network, comprising:
s100, calibrating routing processing transmission time delay D of each satellite nodeHS；
S102, counting queue forwarding waiting time delay D of each satellite node in real timeQW；
S104, calculating the inter-satellite transmission time delay D of two adjacent satellite nodesij；
S106, each satellite node is in a statistical time window TsaInternally counting the forwarding waiting time delay D of all queues of the satellite on each portQWAnd routing processing transmission delay DHSAnd forming neighbor probing message NeighborMsg, NeighborMsg message to count the time window TsaTransmitting at each port of an inter-satellite link for a transmission period;
s108, after other satellite nodes except the satellite receive the NeighborMsg message, generating a one-hop neighbor table, a two-hop neighbor table and a network topology table according to the NeighborMsg message;
s110, calculating the routing table of the local satellite through the generated one-hop neighbor table, two-hop neighbor table and network topology table.
2. The method of claim 1, wherein the S100 further comprises:
s1000, processing and sending time delay D in calibration routingHSThe forward waiting queue is emptied;
s1002, clearing the forwarding waiting queue, and receiving a data packet from a port of the router at a time TRRStarting at the moment T when the data packet completes the code modulation at the baseband of the inter-satellite linkBTAnd (4) ending, namely:
DHS＝TBT-TRR。
3. the method according to claim 1, wherein the S102 further comprises:
the on-board switching forwarding router distributes a forwarding waiting queue for different QoS priority services, data packets in the same queue are sent according to a first-in first-out principle, different queues are scheduled according to a priority scheduling strategy, and the waiting time of each data packet in the queues is dequeuing time ToutAnd the enqueue time TinThe difference of (a) is:
DQW＝Tout-Tin。
4. the method of claim 1, wherein the S104 further comprises:
each satellite stores full-network ephemeris information, and the position coordinates of i star and j star of two adjacent satellites are PiAnd PjThe relative distance between the i star and the j star can be obtained according to the position coordinates, and further the transmission time delay D between the i star and the j star can be obtainedijNamely:
Figure FDA0002624732610000011
wherein C is the speed of light.
5. The method of claim 1, wherein the neighbor probing message NeighborMsg content comprises: local satellite ID, route processing and sending time delay DHSForwarding wait delay DQWMessage sequence number SnNumber of message transfers HnOne-hop neighbor satellite ID, one-hop neighbor satellite communication state and inter-satellite transmission time delay Dij。
6. The method of claim 5, wherein the S108 further comprises:
s1080, after other satellite nodes except the local satellite receive the NeighborMsg message, the ' local satellite ID ' and the ' message serial number S in the NeighborMsg message are utilizedn"make duplicate checking judgment, if received, discard the NeighborMsg message, otherwise, go to S1082;
s1082, judging message forwarding times HnIf yes, the message sending star is the one-hop neighbor node of the local star, a corresponding entry of the local star ID in the one-hop neighbor table is newly established or updated, and the local star ID and the message serial number S in the NeighborMsg message are recorded in the entryn"," routing process transmission delay DHS"," queue forwarding waiting delay DQW"," one-hop neighbor satellite ID "," one-hop neighbor satellite connection state ", and" inter-satellite transmission delay Dij”；
S1084, if the one-hop neighbor satellite communication state corresponding to a certain one-hop neighbor satellite ID in the NeighborMsg message is bidirectional, the one-hop neighbor satellite ID node is a two-hop neighbor node of the same satellite, an item corresponding to the one-hop neighbor satellite ID is newly built or updated in a two-hop neighbor table, and the newly built or updated content comprises routing processing sending time delay DHS"," queue forwarding waiting delay DQW”、“Forward hop satellite ID and inter-satellite transmission delay Dij”；
S1086, judging message forwarding times HnIf the neighbor satellite ID exists in the neighbor list of one hop or the neighbor list of two hops, skipping and not processing; otherwise, judging whether the connection state of the one-hop neighbor satellite ID is bidirectional, and if not, skipping and not processing; if the connection is bidirectional, an entry corresponding to the local star ID in the NeighborMsg message is newly built or updated in the network topology table, and the local star ID and the message sequence number S in the NeighborMsg message are recorded in the entryn"," routing process transmission delay DHS"," queue forwarding waiting delay DQW", one-hop neighbor satellite ID and inter-satellite transmission delay D of the bidirectional connection stateij”。
7. The method of claim 6, wherein the S110 further comprises:
s1100, when calculating each hop route, calculating the total time delay D of the hophThe formula is as follows:
Dh＝DHS+DQW+Dij；
when calculating H-hop route, according to D of each hophAnd calculating the total time delay D according to the following formula:
Figure FDA0002624732610000021
s1102, clearing all table entries in the existing routing table;
s1104, calculating a 1-hop route through the one-hop neighbor table, specifically comprising the following steps:
acquiring the nth neighbor satellite ID of the satellite according to the one-hop neighbor table;
calculating the time delay from the local satellite to the nth 1-hop neighbor satellite as follows: dh_1＝DHS_1+DQW_1+Dij_1；
Traversing N from 1 to N, wherein N one-hop neighbor nodes of the local satellite are provided, and the time delay of the N one-hop neighbor nodes corresponding to the local satellite is recorded in a one-hop neighbor table;
s1106, 2-hop routing is calculated through the two-hop neighbor table, for any two-hop neighbor, a table entry exists in the two-hop neighbor table, and the ID of the previous-hop satellite is equal to one-hop neighbor of the current satellite, so the specific steps of calculating the 2-hop routing table entry of each two-hop neighbor are as follows:
acquiring the Mth 2-hop neighbor satellite ID of the satellite according to the two-hop neighbor table;
calculating the time delay from the local satellite to the m 2-hop neighbor satellite as follows: dh_2＝Dh_1+DHS_2+DQW_2+Dij_2；
Traversing M from 1 to M, wherein M neighbor nodes of the satellite have M, and the two-hop neighbor table records the time delay of the M neighbor nodes of the satellite corresponding to the M neighbor nodes, wherein Dh_1Representing the time delay from the satellite to the one-hop neighbor node corresponding to the satellite;
s1108, calculating h +1 hop routing through a network topology table, wherein h is a natural number greater than or equal to 2, and the specific steps are as follows:
the satellite ID of an entry in the network topology table exists in the routing table, the routing hop number is equal to h, and the 'one-hop neighbor satellite node' of the entry is judged as follows;
if the 'one-hop neighbor satellite node' has a corresponding entry in the routing table, performing time delay comparison; otherwise, the one-hop neighbor satellite node is a new h + 1-hop node, and the routing entry of the h + 1-hop node is calculated;
acquiring the ID of the kth + 1-hop neighbor satellite of the satellite according to the h + 1-hop neighbor table;
calculating the time delay from the satellite to the k h + 1-hop neighbor satellite as follows: dh_h+1＝Dh_h+DHS_h+1DQW_h+1+Dij_h+1；
Traversing K from 1 to K, wherein K neighbor nodes of all h +1 hops of the satellite are provided, and the time delay of the K neighbor nodes of the satellite corresponding to the K neighbor nodes of the h +1 hops is recorded in an h +1 hop neighbor table and is used for calculating the time delay of the K neighbor nodes of the satellite corresponding to the K neighbor nodesIf there are 1 or more paths from the satellite to the h +1 hop neighbor node, the path with shorter time delay is reserved, Dh_hAnd representing the time delay from the satellite to the h-hop neighbor node corresponding to the satellite.
8. The method of claim 7, wherein the H of NeighborMsg isn+1, when the number of times of forwarding Hn+1≤HmaxWhen, the NeighborMsg message is forwarded, otherwise it is not forwarded, where HmaxThe maximum forwarding times of the whole network.
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